Method and Apparatus for Providing Continuous Access to Shared Tape Drives from Multiple Virtual Tape Servers Within a Data Storage System

1. A method for providing continuous access to shared tape drives from multiple virtual tape server (VTS) nodes, said method comprising: connecting a first VTS node and a second VTS node to a plurality of tape drives via a plurality of switches, wherein said first VTS node includes an active database and said second VTS node includes a standby database; redirecting all requests received by said standby database to said active database; in response to a volume mount request on a physical volume, placing a lock on a tape drive table by one of said two VTS nodes handling said volume mount request to preventing any access to said tape drive table from one of said two VTS nodes not handling said volume mount request; selecting an available physical tape drive to mount said physical volume and marking an entry within said tape drive table to claim ownership of said physical tape drive by said VTS node handling said volume mount request; sending drive reservation request to said physical tape drive to prevent any access to said physical tape drive, and releasing said lock on said tape drive table by said VTS node handling said volume mount request; and performing said volume mount request by said VTS node handling said volume mount request.

2. The method of claim 1 , wherein said method further includes returning an error status in a determination that said physical volume is not mountable.

3. The method of claim 1 , wherein said method further includes returning an error status in a determination that no physical tape drive is available to mount said physical volume.

4. The method of claim 1 , wherein said first and second VTS nodes communicate with each other via a computer network.

5. The method of claim 1 , wherein said tape drive table includes a composite view of all physical tape drives shared between said two VTS nodes.

6. The method of claim 1 , wherein said two VTS nodes communicate each other's system health via periodic “heart beats” such that when one of said two VTS node fails and another one of said two VTS nodes takes ownership of devices from said failed VTS node.

7. A computer storage medium having a computer program product for providing continuous access to shared tape drives from multiple virtual tape server (VTS) nodes, said computer storage medium comprising: computer program code for connecting a first VTS node and a second VTS node to a plurality of tape drives via a plurality of switches, wherein said first VTS node includes an active database and said second VTS node includes a standby database; computer program code for redirecting all requests received by said standby database to said active database; computer program code for, in response to a volume mount request on a physical volume, placing a lock on a tape drive table by one of said two VTS nodes handling said volume mount request to preventing any access to said tape drive table from one of said two VTS nodes not handling said volume mount request; computer program code for selecting an available physical tape drive to mount said physical volume and marking an entry within said tape drive table to claim ownership of said physical tape drive by said VTS node handling said volume mount request; computer program code for sending drive reservation request to said physical tape drive to prevent any access to said physical tape drive, and releasing said lock on said tape drive table by said VTS node handling said volume mount request; and computer program code for performing said volume mount request by said VTS node handling said volume mount request.

8. The computer storage medium of claim 7 , wherein said computer storage medium further includes computer program code for returning an error status in a determination that said physical volume is not mountable.

9. The computer storage medium of claim 7 , wherein said computer storage medium further includes computer program code for returning an error status in a determination that no physical tape drive is available to mount said physical volume.

10. The computer storage medium of claim 7 , wherein said first and second VTS nodes communicate with each other via a computer network.

11. The computer storage medium of claim 7 , wherein said tape drive table includes a composite view of all physical tape drives shared between said two VTS nodes.

12. The computer storage medium of claim 7 , wherein said computer storage medium further includes computer program code for allowing said two VTS nodes to communicate each other's system health via periodic “heart beats” such that when one of said two VTS node fails and another one of said two VTS nodes takes ownership of devices from said failed VTS node.